Adjustable time delay relay



April 17, 1945. s. BURGWIN ADJUSTABLE TIME DELAY RELAY Filed Feb. 2, 1943 V////////////% w 2 f p m F H WITNESSES:

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Patented Apr. 17, 1945 misses ADJUSTABLE TIME DELAY RELAY Stephen L. Burgwin, Forest Hills, Pa., assignor to Westinghouse Electric & Manufacturing Com- I pany, East Pittsburgh, Pa., a corporation of Pennsylvania 1 Application February 2, 194$,Serial No. 474,438

3 Claims.

This invention relates to time limit relays and, more particularly, to adjustable means in a direct current relay for varying the time period of operation of the relay.

The subject matter of this application is related to that disclosed in the copending applications of Ralph E. Immel, respectively, Serial No. 119,715, filed November 19, 1941, and Serial No. 453,062, filed July 31, 1942.

Time delay relays having an armature actuated by spring biasing means only when the strength of the decaying flux is less than the force of the biasing means are well known. In such relays the time limit of operation is measured by the time which is required for the residual magnetism in a magnetic circuit to decay from a saturated condition to a point at which the force of a biasing means is sufiicient to overcome the attractive force exerted on the armature by the residual magnetism. Forms of such relays are shown in the patent to W. G. Cook, No. 1,753,983, issued April 8. 1930, and the patent to W. Schaelchlin et al., No. 1,979,709, issued November 6, 1934. As pointed out in these patents the time limit characteristics of a relay may be varied by inserting non-magnetic shims between the operating armature and the portion of the magnetic circuit adapted to actuate the armature. However, this method of adjusting the time limit characteristics necessitates the dismantling of the relay in order to substitute shims of different thicknesses and requires the use of shims manufactured to close tolerances since the relay is extremely sensitive to a small variation in the thickness of the shim.

One of the principal objects of this invention is to provide a direct current inductive time limit relay with. a rectilinearly movable member in the magnetic circuit thereof which is manually adjustable to vary the reluctance of the circuit and the time limit characteristics of the relayv A further object is to provide a rectilinearly movable adjusting member of the character referred to which is so arranged with respect to the magnetic circuit that a thick gap and a short gap a e provided and connected in parallel in such circuit.

A further object is to provide an adjusting member of the character referred to in which given movement of the member necessary to effect a given change in the reluctance of the circuit is increased to a maximum.

Other objects and advantages will become apparent from a study of the following specification and the accompanying drawing in which;

Figure 1 is a side elevational view of an inductive time limit relay constructed in accordance with the principles of this invention;

Figure 2 is a sectional view taken substantially on the line I1-II of Fig. 1; and

Figure 3 is a view similar to Fig. 1 illustrating a modified form of relay.

Referring to the drawing, the numeral 5 designates an armature mounted on a magnetic support indicated as a whole by the numeral 2 constituting a part of a magnetic circuit for actuating the armature l. The armature l is connected to the support 2 for pivotal movement with respect thereto by a hinge construction 3 having adjustable sprin biasing means 4 for pivotally moving the armature i counterclockwise in a manner well known in the art. A core member 5 carrying a copper sleeve 6, an energizing coil 1, and a neutralizing coil 3 is mounted on the support 9. The parts thus far described form no part per se of this invention and. the above-mentioned patents to Cook and Schaelchlin may be referred to for a complete description of the construction and operation of such parts, this invention being limited to the adjusting means to be described.

Referring to Fig. 1, the magnetic circuit cornprises an L.-shaped member 6 and a supporting plate it on which the armature I and its support 2 are mounted by the hinge 3, the member 9 and plate it both being formed by magnetizable material. The plate so is mounted on a leg I l of the member 3 by rivets l2 and washers 13 formed of non-magnetizable material, the washers l3 functioning to space the plate i5 from the leg H and provide a gap M therebetween. The washers [3 are so arranged that the facing surfaces of the plate it! and leg H defining the gap it are parallel to each other. In this manner the magnetic circuit is separated into two parts having a gap there'between and it will be noted that the particular arrangement is such that the crosssectional area of the gap 14 in a plane parallel to the facing surfaces of the plate IE] and the leg H is several times the cross-sectional area of the magnetic circuit.

For varying the reluctance of the magnetic circuit and the time characteristics of the relay, a non-magnetic spacer I 5 and a magnetic spacer 18 are positioned in the gap it. The non-magnetic spacer 15 comprises a relatively thin sheet of nonmagnetic material such as copper mounted on the inner. surface of the plate to. The magnetic spacer It comprises a rectangular plate of magnetizable material such as iron slidably mounted in the space between the non-magnetic spacer I6 and the leg I I. The plate I6 is slidably mounted for movement from a position substantially filling the gap I4 as shown in solid lines in Fig. 1 to a position substantially out of the gap I4 as indicated by the dotted lines to vary the reluctance of the magnetic circuit. The arrangement of the spacers I and I6 provides a thick gap having a thickness t and a thin gap having a thickness t1 connected in parallel in the magnetic circuit between the members Ill and II. The thickness ii of the thin gap is measured by the thickness of the non-magnetic spacer I5. The thickness of the thick gap t is measured by the thickness of the non-magnetic spacer I 5 plus the thickness of the air space between the surface of the spacer I5 and the surface of the leg I I.

The cross-sectional area of the gap I4 may be consideredsubstantially the same as the surface area of the non-magnetic spacer I 5 or the sum of the areas AI and A2 in Fig. 2 the area AI being the cross-sectional area of the thin gap or the surface of the spacer I5 covered by the member I8. and the area A2 being the cross-sectional area of the thick gap or the area of the spacer I5 not covered by the spacer I6. Since the reluctance of a magnetic circuit is proportional to t/A, where t is the thickness and A the area of the gap, it will be seen that the reluctance provided by the gap I4 is proportional to the sum of t/AZ plus ti/Al. Since t and ti are constants and AI and A2 are variable in accordance with the position of the adjustable member I6, it will be seen that the reluctance of the magnetic circuit 2 is variable in accordance with the position of the ad justable member It. When the member I6 is in the position as indicated by the solid lines in Fig. 1, the reluctance of the circuit 2 is a minimum. As the member I6 is moved to the position indicated by the dotted lines the reluctance of the magnetic circuit will be increased from a minimum to a maximum.

A relay constructed in accordance with the showing of Fig. 1 and employing a non-magnetic spacer I5 having a thickness of 14 mils and a magnetic spacer I6 having a thickness of .136 inch and in which the cross-sectional area of the gap I4 is approximately seven times of that of the magnetic circuit will be found to give substantially the same range of adjustment as will be had in a similar relay in which the adjustnetic shims between the armature I and face of the pole 5 having a thickness from 2 to 20 mils.

A much finer adjustment of the reluctance of Q the magnetic circuit may be had by the preferred construction of making the area of the gap I4 several times the cross-sectional area of the magnetic circuit. In this manner, amuch larger movement of the adjusting member I6 is required to effect a given change in the reluctance of the magnetic circuit than would be the case if a single gap were provided. The provision of the two gaps, made possible by increasing the area of the gap in the circuit, makes the magnetic circuit less responsive to small movements of the construction illustrated in Fig. 1. The essential difference in the modification of Fig. 3 lies in the connection of the armature I by the hinge 3 directly to the L-shaped magnetic support 9 and in the changed construction of the core member 5". The core member 5' in this showing comprises a cylindrical sleeve I! of magnetizable material connected to the support 9 and a cylindrical plug I8 of magnetizable material. The external diameter of the plug I8 is made smaller than the internal diameter of the sleeve I! and the plug I8 is positioned and supported concentrically within the sleeve IT by a spacing rin Iii formed of non-magnetizable material. In this manner an annular air gap 20 is arranged between the sleeve ll and plug I8 of the core member 5' which constitutes a part of the magnetic circuit. Adjustment is had in this arrangement by means of a cup shaped member ZI formed of magnetizable material having a cylindrical sleeve portion 22. The external surface of the sleeve 22 is slidably engaged with the inner surface of the sleeve IT to provide a good magnetic connection therebetween and the sleeve 22 has an internal diameter greater than the-external diameter of the plug I8. An adjusting member 23 has a threaded connection with the plug I8 and is connected to the cup M for adjusting the position of the sleeve 22 with respect to the plug I8.

The sleeve 22 is receivable in the annular space 26 as shown in Fig. 3 to provide a thick gap 24 and a thin gap 25. By rotating the member 23, the sleeve 22 will be moved into and out of space 20 to vary simultaneously the respective areas of the thick gap 23 and the thin gap 25 in the same manner as is bad by movementof the adjusting member IS in the construction illustrated in Fig. 1. In this respect the member 16 of Fig. 1 may be provided with a threaded adjusting member similar to the member 23 for adjusting its position with respect to the magnetic support 2. It will be apparent that the reluctance of the circuit shown in Fig. 2 will be a minimum when the sleeve is moved to its extreme right-hand position in the annular space 29 and will be increased to a maximum upon withdrawal of the sleeve out of such space.

From the foregoing it will. be noted that both modifications illustrated provide a rectilinearly movable member in the magnetic circuit of a time-limit relay. Moreover, it will be noted that movement of the adjusting member to various positions is effective to change the reluctance of the magnetic circuit by varying the air gap between difierent portions of the circuit. By arranging the gap between such portions of the circuit to provide a thick gap and a thin gap connected in parallel in such circuit and in which the areas of such gaps are respectively increased and decreased upon movement of the adjusting member in a given direction, an extremely accurate adjustment of the reluctance of th magnetic circuit may be had without the necessity of expensive machining operations in the construction of the relay or careful movements of the adjusting member.

Since certain changes maybe made in the above construction and difierent embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter contained in theabove description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

forth between two positions, means biasing said armature to one of said positions, a core on said support for moving said armature to the other of said positions comprising a cylindrical sleeve, a cylindrical plug having a diameter less than the internal diameter of said sleeve, and non-magnetic means concentrically positioning said plug with respect to said sleeve to provide an annular space therebetween, and a cylindrical sleeve adjusting member having an internal diameter greater than the diameter of said plug and its external surface in sliding engagement with the internal surface of said first sleeve, said adjusting member being movable into and out of said annular space to vary the reluctance of the magnetic circuit.

2. In an electromagnetic time-limit relay, in combination, a magnetic support, an armature mounted on said support for movement back and forth between two positions, means biasing said armature to one of said positions, a core on said support for moving said armature to the other of said positions comprising a cylindrical sleeve, a cylindrical plug having a diameter less than the internal diameter of said sleeve, and non-magnetic means concentrically positioning said plug with respect to said sleeve to provide an annular space therebetween, and a cylindrical sleeve adjusting member having an internal diameter greater than the diameter of said plug and its external surface in sliding engagement with the internal surface of said first named sleeve, the relation of both of said sleeves with respect to said plug providing a thin air gap and a thick air gap connected in parallel in said circuit, said sleeve adjusting member being movable into and out of said annular space to vary the areas of both of said gaps and thereby the reluctance of the magnetic circuit.

3. In an electromagnetic time-limit relay, in combination, a magnetic support, an armature mounted on said support for movement back and forth between two positions, means biasing said armature to one of said positions, a core on said support for moving said armature to the other of said positions comprising a cylindrical sleeve, a cylindrical plug having a diameter less than the internal diameter of said sleeve, and non-magnetic means concentrically positioning said plug with respect to said sleeve to provide an annular space therebetween, and a cylindrical sleeve adjusting member having an internal diameter greater than the diameter of said plug and its external surface in sliding engagement with the internal surface of said first sleeve, the relation of both of said sleeves with respect to said plug providing a thin air gap and a thick air gap connected in parallel in said circuit, and means for adjusting the position of said adjusting sleeve in said annular space to vary the areas of both of said gaps and thereby the reluctance of the magnetic circuit.

STEPHEN L. BURGWIN. 

